You have 8 balls. One of them is defective and weighs less
than others. You have a balance to measure balls against
each other. In 2 weighings how do you find the defective
one?

Answer Posted / fahad sheikh

Divide the 8 balls into three groups
G1: 1,2,3
G2: 4,5,6
G3: 7,8

Weight 1: Weight G1 against G2, if G1=G2 then lighter ball
is in G3. If G1<G2, then lighter ball is in G1 otherwise is
in G2

Weight 2: If lighter ball is in G3, then weight 7 and 8 no
ball against eachother and find the lighter one.
If lighter ball is in G1 or G2 then divide the group into
two further groups
G4: 1,2
G5: 3
Now weight ball no 1 and 2 against eachother. if 1==2 then
defective is 3 otherwise ball with lesser weight is the
lighter one.

Is This Answer Correct ?    10 Yes 2 No



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